EnOcean STM 550U User manual

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

Patent protected:

WO98/36395, DE 100 25 561, DE 101 50 128,

WO 2004/051591, DE 103 01 678 A1, DE 10309334,

WO 04/109236, WO 05/096482, WO 02/095707,

US 6,747,573, US 7,019,241

Observe precautions! Electrostatic sensitive devices!

EnOcean Multisensor For IoT Applications

STM 550 / EMSI

17.11.2020

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

REVISION HISTORY

The following major modifications and improvements have been made to this document:

Version

Author

Reviewer

Date

Major Changes

1.0

MKA

TM, EM,

MH, MF

19.02.2020

First public release

1.1

MKA

18.05.2020

Added description of mechanical interface

Added description of product variants

1.2

MKA

30.06.2020

Added illustration of backup battery interface

1.3

MKA

03.09.2020

Added ARIB certificate

1.4

MKA

17.11.2020

Update for revision DB-06

Published by EnOcean GmbH, Kolpingring 18a, 82041 Oberhaching, Germany

www.enocean.com, info@enocean.com, phone +49 (89) 6734 6890

Important!

This information describes the type of component and shall not be considered as assured

characteristics. No responsibility is assumed for possible omissions or inaccuracies. Circuitry

and specifications are subject to change without notice. For the latest product specifications,

refer to the EnOcean website: http://www.enocean.com.

As far as patents or other rights of third parties are concerned, liability is only assumed for

modules, not for the described applications, processes and circuits.

EnOcean does not assume responsibility for use of modules described and limits its liability

to the replacement of modules determined to be defective due to workmanship. Devices or

systems containing RF components must meet the essential requirements of the local legal

authorities.

The modules must not be used in any relation with equipment that supports, directly or

indirectly, human health or life or with applications that can result in danger for people,

animals or real value.

Components of the modules are considered and should be disposed of as hazardous waste.

Local government regulations are to be observed.

Packing: Please use the recycling operators known to you.

 
USER MANUAL 
 
 
 
STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS 
 
© 2020 EnOcean | www.enocean.com F-710-017, V1.0       STM 550 / EMSI User Manual | v1.4 | November 2020 | Page 3/97 
 
TABLE OF CONTENT 
General description ........................................................................................ 7 
1  Basic functionality ......................................................................................... 7 
2  Product variants ............................................................................................ 8 
3  Technical data ............................................................................................... 9 
4  Environmental conditions ............................................................................... 9 
5  Packaging information .................................................................................. 10 
5.1  STM 550 ............................................................................................. 10 
5.2  STM 550 installation kit ........................................................................ 10 
5.3  EMSI .................................................................................................. 10 
6  Ordering information ................................................................................... 10 
Functional overview ..................................................................................... 11 
1  Product description ...................................................................................... 11 
2  Functional modes ........................................................................................ 11 
2.1  Standard operation mode ..................................................................... 12 
2.2  Standby (Sleep) mode .......................................................................... 12 
2.3  Learn mode......................................................................................... 12 
2.4  Function test mode .............................................................................. 12 
2.5  Illumination test mode ......................................................................... 13 
2.6  Acceleration test mode ......................................................................... 13 
2.7  Factory reset mode .............................................................................. 13 
3  Reporting interval ........................................................................................ 14 
3.1  Energy considerations .......................................................................... 14 
3.2  Standard reporting interval ................................................................... 15 
3.3  Illumination-controlled reporting interval ................................................ 16 
3.4  Temperature-controlled reporting interval ............................................... 17 
3.5  Humidity-controlled reporting interval .................................................... 18 
3.6  Acceleration-controlled reporting interval ................................................ 19 
3.7  Magnet contact sensor-controlled reporting interval ................................. 20 
3.8  Arbitration between reporting intervals ................................................... 20 
Sensor functionality ..................................................................................... 21 
1  Light level sensor ........................................................................................ 21 
2  Solar cell .................................................................................................... 21 
3  Temperature sensor..................................................................................... 22 
4  Humidity sensor .......................................................................................... 22 
5  Acceleration sensor...................................................................................... 23 
5.1  Wake on acceleration ........................................................................... 24 
5.2  Acceleration sensor parameters ............................................................. 24 
6  Magnet contact sensor ................................................................................. 25 
Product interface ......................................................................................... 26 
1  LED ........................................................................................................... 27 
2  LRN button ................................................................................................. 27 
3  Backup battery ........................................................................................... 28 
3.1  Safety remarks .................................................................................... 28 
4  Product label ............................................................................................... 29 

 
USER MANUAL 
 
 
 
STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS 
 
© 2020 EnOcean | www.enocean.com F-710-017, V1.0       STM 550 / EMSI User Manual | v1.4 | November 2020 | Page 4/97 
 
Radio communication ................................................................................... 30 
1  Radio Frame format ..................................................................................... 30 
1.1  ERP1 frame format .............................................................................. 30 
1.2  ERP2 frame format .............................................................................. 30 
2  EnOcean Equipment Profiles (EEP) and SIGNAL telegrams ................................ 31 
2.1  STM 550 supported EEP ........................................................................ 31 
2.2  EEP structure ...................................................................................... 32 
2.3  1BS telegram ...................................................................................... 33 
2.4  4BS telegram ...................................................................................... 33 
2.5  VLD telegram ...................................................................................... 33 
2.6  UTE (Universal Teach-in) telegram ......................................................... 33 
2.7  Signal telegram ................................................................................... 34 
Security ..................................................................................................... 35 
1  Basic concepts ............................................................................................ 35 
1.1  Telegram encryption ............................................................................ 35 
1.2  Telegram authentication ....................................................................... 36 
1.3  Dynamic security key modification ......................................................... 37 
2  Security parameters .................................................................................... 38 
2.1  EURID ................................................................................................ 38 
2.2  Security key ........................................................................................ 38 
2.3  Rolling code ........................................................................................ 38 
2.4  Security algorithm ............................................................................... 38 
3  STM 550 security implementation .................................................................. 39 
Commissioning ............................................................................................ 40 
1  Radio-based commissioning .......................................................................... 41 
2  QR code commissioning ............................................................................... 41 
3  Commissioning via NFC interface ................................................................... 41 
NFC interface .............................................................................................. 42 
1  NFC interface parameters ............................................................................. 42 
2  NFC access protection .................................................................................. 42 
3  Using the NFC interface ................................................................................ 43 
3.1  PC with dedicated NFC reader ............................................................... 43 
3.2  Android or iOS smartphone with NFC...................................................... 43 
4  NFC interface functions ................................................................................ 44 
4.1  NFC interface state machine .................................................................. 44 
4.2  IDLE state ........................................................................................... 45 
4.3  READY 1 state ..................................................................................... 45 
4.4  READY 2 state ..................................................................................... 45 
4.5  ACTIVE state ....................................................................................... 45 
4.6  Read command ................................................................................... 46 
4.7  Write command ................................................................................... 46 
4.8  Password authentication (PWD_AUTH) command ..................................... 47 
NFC registers .............................................................................................. 48 
1  NFC memory areas ...................................................................................... 48 
2  Device identification NDEF ............................................................................ 49 
3  User information NDEF ................................................................................. 49 

 
USER MANUAL 
 
 
 
STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS 
 
© 2020 EnOcean | www.enocean.com F-710-017, V1.0       STM 550 / EMSI User Manual | v1.4 | November 2020 | Page 5/97 
 
4  NFC HEADER............................................................................................... 50 
4.1  NFC HEADER area structure .................................................................. 50 
5  CONFIGURATION ......................................................................................... 51 
5.1  Using the NFC configuration functionality ................................................ 51 
5.2  CONFIGURATION area structure ............................................................ 51 
5.3  NFC_PIN_CODE ................................................................................... 52 
5.4  PRODUCT_ID ...................................................................................... 52 
5.5  USER_KEY .......................................................................................... 53 
5.6  SECURITY_KEY_MODE .......................................................................... 53 
5.7  SECURITY_MODE ................................................................................. 54 
5.8  EEP .................................................................................................... 55 
5.9  SIGNAL .............................................................................................. 56 
5.10  LED_MODE ......................................................................................... 57 
5.11  FUNCTIONAL_MODE ............................................................................. 58 
5.12  STANDARD_TX_INTERVAL .................................................................... 59 
5.13  THRESHOLD_CFG1............................................................................... 60 
5.14  THRESHOLD_CFG2............................................................................... 62 
5.15  LIGHT_SENSOR_CFG ........................................................................... 63 
5.16  ACC_SENSOR_CFG .............................................................................. 64 
5.17  SOLAR_THRESHOLD............................................................................. 65 
5.18  SOLAR_TX_INTERVAL .......................................................................... 66 
5.19  LIGHT_THRESHOLD ............................................................................. 67 
5.20  LIGHT_TX_INTERVAL ........................................................................... 68 
5.21  ACCELERATION_THRESHOLD ................................................................ 69 
5.22  ACCELERATION_TX_INTERVAL .............................................................. 70 
5.23  TEMPERATURE_THRESHOLD ................................................................. 71 
5.24  TEMPERATURE_TX_INTERVAL ............................................................... 72 
5.25  HUMIDITY_THRESHOLD ........................................................................ 73 
5.26  HUMIDITY_TX_INTERVAL ...................................................................... 74 
5.27  MAGNET_CONTACT_TX_INTERVAL ......................................................... 75 
5.28  ILLUMINATION_TEST_RESULT ............................................................... 76 
6  USER DATA ................................................................................................ 76 
Mechanical interface .................................................................................... 77 
1  Top view .................................................................................................... 77 
2  Bottom view ............................................................................................... 78 
3  Cut view (A-A) ............................................................................................ 79 
4  Front view .................................................................................................. 79 
5  Side view ................................................................................................... 80 
Installation recommendations ....................................................................... 81 
1  Setup instructions ....................................................................................... 81 
2  Temperature and humidity sensor ................................................................. 82 
3  Acceleration sensor...................................................................................... 83 
3.1  Device orientation use cases ................................................................. 83 
3.2  Device acceleration use cases................................................................ 85 
3.3  Installation suggestions ........................................................................ 85 
4  Illumination measurement ............................................................................ 86 
4.1  Ambient light sensor ............................................................................ 86 
4.2  Solar cell ............................................................................................ 86 

 
USER MANUAL 
 
 
 
STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS 
 
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5  Magnet contact sensing ................................................................................ 88 
6  Energy harvesting ....................................................................................... 88 
7  NFC configuration ........................................................................................ 89 
Regulatory notes ......................................................................................... 90 
1  European Union........................................................................................... 90 
1.1  Declaration of conformity ...................................................................... 90 
1.2  Waste treatment .................................................................................. 90 
2  FCC (United States) ..................................................................................... 91 
2.1  FCC Grant Of Equipment Authorization ................................................... 91 
2.2  FCC (United States) regulatory statement ............................................... 92 
2.3  FCC usage conditions ........................................................................... 92 
2.4  FCC OEM requirements ......................................................................... 93 
3  ISED (Industry Canada) ............................................................................... 94 
3.1  ISED Technical Acceptance Certificate .................................................... 94 
3.2  ISED (Industry Canada) regulatory statement ......................................... 95 
4  ARIB (Japan) .............................................................................................. 96 
4.1  ARIB construction type conformity certificate .......................................... 96 
Product history ............................................................................................ 97 
   

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

1 General description

This user manual describes the functionality of the STM 550 EnOcean multisensor module, of

the STM 550 Installation Kit and the EMSI Easyfit Multisensor in the following frequency

variants:

◼ STM 550, STM 550 KIT and EMSIA using 868.3 MHz radio (main market Europe)

◼ STM 550U, STM 550U KIT and EMSIU using 902.875 MHz radio (main market US)

◼ STM 550J, STM 550J KIT and EMSIJ using 928.35 MHz radio (main market Japan)

The term “STM 550” is used throughout this user manual to describe all variants unless

otherwise noted.

1.1 Basic functionality

STM 550 is a flexible self-powered multisensor module family capable of measuring temper-

ature, humidity, illumination, magnet contact status and acceleration. It enables the realiza-

tion of energy harvesting wireless sensors for light, building or industrial control systems

communicating using the EnOcean radio standard.

STM 550 uses the same mechanical form factor as the industry standard PTM 21x modules

from EnOcean.

STM 550 implements the following sensors:

◼ Temperature

◼ Humidity

◼ Illumination

◼ Acceleration

◼ Magnet contact

STM 550 will report periodically (by default approximately every 60 seconds, configurable via

NFC) the latest measurements of these sensors. In addition, STM 550 can also report its

internal energy level and the amount of light available at the solar cell.

STM 550 will report immediately if the status (open / closed) of the magnet contact changes

or if a change in acceleration measured by the acceleration sensor exceeds a user-defined

threshold for the first time.

Radio telegrams transmitted by STM 550 can be encrypted and authenticated using AES-128

security based on a device-unique private key and a sequence counter in accordance to the

EnOcean Alliance Security Specification. This ensures integrity, confidentiality and authentic-

ity of the transmitted telegrams and prevents telegram replay (retransmission of previously

transmitted telegrams).

STM 550 is self-supplied via an integrated solar cell which generates the energy required for

its operation. For cases where ambient light is not sufficiently available, STM 550 provides

the option to mount a CR1632 backup battery.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

1.2 Product variants

STM 550 is available in three different product and packaging variants:

◼ STM 550 is the multisensor module in original PTM module form factor intended for

integration into OEM housings. It is provided in tray and box packaging of 100 units

per box.

◼ STM 550 Installation Kit combines the STM 550 multisensor module with a wall

mount, a design frame, a magnet (for magnet sensor functionality) and an adhesive

mounting tape into a ready to use product. It is provided in tray and box packing of

100 units per box.

◼ EMSI Easyfit Multisensor contains the same components as STM 550 Installation Kit

but is provided in single unit packaging with 10 single packaged units per box.

Figure 1 below shows the STM 550 module on the left and the finished product combining

the STM 550 module with wall mount and design frame on the right.

Figure 1 – STM 550 module (left) and finished product (right)

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

1.3 Technical data

Antenna

Integrated helix antenna

Transmission frequency / power

STM 550: 868.300 MHz / +5 dBm

(3)

STM 550U: 902.875 MHz / + 99 dBµV

STM 550J: 928.350 MHz / 0 dBm

Transmission data rate

125 kbit/s

Communication range (for guidance only)

200 m free field

30 m indoor environment

Temperature measurement range / accuracy

-20 °C … +60 °C / +- 0.3 K

(1)

Humidity measurement range / accuracy

0 … 100 % r.h. / +- 3% r.h.

(1)

Illumination measurement range / accuracy

0 … 65000 lux / +-10 %

Acceleration measurement range / accuracy

+- 2 g / +-0.03 g

Acceleration threshold for immediate report

0.03 g (default, configurable via NFC)

Update rate (excl. random offset)

Every 60 seconds (configurable via NFC)

Device configuration

LRN button and NFC interface

User notification

LED (red)

Supported EEP (selectable via NFC)

D2-14-41 (default)

D2-14-40, A5-02-05, A5-04-01, A5-04-03

A5-06-02, A5-06-03, A5-14-05, D5-00-01

Power supply

Integrated solar cell

Minimum light level for self-supplied operation

200 lux for 6 hours per day

(2)

Operating time in darkness

4 days (after full charge)

Backup power supply (optional)

CR1632

Operation time with backup battery

Infrequent bright light (200 lux for 2 hrs per day)

Consistent low light (50 lux for 6 hrs per day)

Total Darkness

Renata CR1632 (137 mAh)

7 years

6 years

4.5 years

Dimensions (Module)

40 mm x 40 mm x 13 mm

Dimensions (Finished product)

49 mm x 49 mm x 13 mm

Note 1: STM 550 is designed for indoor use only and should only be used in the environmental conditions

specified below

Note 2: Minimum light level required for self-supplied operation with the default product configuration.

See chapter 2.3.1 for other scenarios

Note 3: Transmission power has been increased to +10 dBm starting with STM 550 product revision DB-06

1.4 Environmental conditions

Operating Temperature

-5 °C … +45 °C (indoor use in dry rooms only)

Humidity

0% to 90% r.h. (non-condensing)

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

1.5 Packaging information

1.5.1 STM 550

STM 550 is delivered in a box of 100 units packed onto 10 trays of 10 units each.

Packaging Unit

100 units

Packaging Method

10 modules per tray, 10 trays per box

Tray Dimensions

205 mm x 166 mm x 20 mm

Box Dimensions

205 mm x 176 mm x 174 mm

1.5.2 STM 550 installation kit

The STM 550 installation kit consists of one box with 100 units STM 550 modules (as de-

scribed above) together with one box of 100 units of installation material.

Packaging Unit 100 units

Packaging Method 1 large outer box containing 2 smaller inner boxes

Inner box 1: 100 units STM 550B (same as above)

Inner box 2: 100 units installation material

Outer Box Dimensions 360 mm x 234 mm x 178 mm

Inner Box Dimensions 232 mm x 176 mm x 174 mm

1.5.3 EMSI

EMSI consists of one box with 10 single unit packages where each package contains one STM

550 module together with the installation material.

Packaging Unit Individual unit packaging

Individual Unit Dimensions 75 mm x 75 mm x 28 mm

Packaging Method 10 individual unit packages within one box

Box Dimensions 300 mm x 90 mm x 90 mm

1.6 Ordering information

Product

Type

Ordering Code

Frequency

STM 550

STM 550U

STM 550J

Module only

100 unit packaging

S6201-K516

S6251-K516

S6261-K516

868.300 MHz

902.875 MHz

928.350 MHz

STM 550 KIT

STM 550U KIT

STM 550J KIT

Module with installation material

100 unit packaging

B6201-K516

B6251-K516

B6261-K516

868.300 MHz

902.875 MHz

928.350 MHz

EMSI

EMSIU

EMSIJ

Module with installation material

Single unit packaging

E6201-K516

E6251-K516

E6261-K516

868.300 MHz

902.875 MHz

928.350 MHz

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2 Functional overview

2.1 Product description

The energy-harvesting multisensor module STM 550 provides wireless sensing functionality

without batteries. Power is provided by a connected solar cell. STM 550 transmits sensor data

using the EnOcean radio standard.

STM 550 operates fully self-powered (no batteries required) when sufficient available ambient

light (200 Lux for 6 hours per day) is available. In this configuration it is fully maintenance-

free.

For cases where sufficient ambient light is not available there is the option to mount a CR1632

backup battery.

Radio telegrams transmitted by STM 550 can be authenticated and encrypted using AES-128

security based on a device-unique private key and a sequence counter in accordance to the

EnOcean Alliance Security Specification. This ensures integrity, confidentiality and authentic-

ity of the transmitted telegrams and prevents telegram replay (retransmission of previously

transmitted telegrams).

2.2 Functional modes

STM 550 supports seven functional modes:

◼ Standard operation mode

◼ Standby (Sleep) mode

◼ Learn mode

◼ Function test mode

◼ Illumination test mode

◼ Acceleration test mode

◼ Factory reset mode

Out of the box, STM 550 will be in standby mode to conserve energy during

transport and storage. Upon initial setup, STM 550 has to be set to standard op-

eration mode by pressing the LRN button shortly as described in chapter 11.1 or

via the NFC interface as described in chapter 9.5.11

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.2.1 Standard operation mode

During standard operation, STM 550 wakes up periodically and reports the current sensor

status using data telegrams. The STM 550 wake-up timer is by default configured to wake-

up STM 550 approximately every 60 seconds. The wake-up intervals are affected at random

(i.e. a small random offset is added or subtracted) in order to increase the robustness of the

radio transmission and to comply with regulatory requirements.

If acceleration exceeding the configured threshold is detected for the first time after a period

without exceeding this threshold then STM 550 wakes up immediately (wake on acceleration

event). Likewise, if the status of the magnet contact changes (from open to closed or vice

versa) then this is reported immediately as well (wake on magnet contact event).

2.2.2 Standby (Sleep) mode

Standby (sleep) mode is the lowest power mode of STM 550 and is the out of the box state

of STM 550 upon delivery. It is intended to be used during extended periods without operation

such as device storage or transport.

In standby mode, STM 550 stops operation and conserves as much energy as possible. All

functionality – except those needed to return to standard operation mode – are disabled in

this mode.

Standby mode can be selected using the LRN button as described in chapter 4.1 or using the

MODE field of the FUNCTIONAL_MODE NFC register as described in chapter 9.5.11. Upon

entering standby mode, STM 550 will send a SIGNAL telegram of type 0x0E as described in

chapter 5.2.7.

2.2.3 Learn mode

In learn mode, STM 550 will transmit a Teach-in telegram to communicate its source address

(EURID), the EnOcean Equipment Profile (EEP) that it currently uses and – if applicable -

security mode and security information to a receiver. After that transmission, STM 550 will

return to standard operation mode.

Learn mode can be selected using the LRN button as described in chapter 4.1 or using the

MODE field of the FUNCTIONAL_MODE NFC register as described in chapter 9.5.11.

2.2.4 Function test mode

In Function Test Mode, STM 550 will measure and report the status of the integrated sensors

at the highest possible rate to verify the sensor functionality.

STM 550 can be set into function test mode via the LRN button as described in chapter 4.1

or via the MODE field of the FUNCTIONAL_MODE NFC register as described in chapter 9.5.11.

Function Test Mode will be stopped once the LRN button is pressed or the functional mode is

changed via the NFC interface.

 
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2.2.5  Illumination test mode 
 
During installation, STM 550 can measure and report the amount of ambient light available 
at its solar cell in order to determine a suitable installation location as discussed in chapter 
11.5.  
 
Upon activation of light test mode, STM 550 will first wait for 15 seconds so that the installer 
can leave the area to ensure a relevant measurement result. 
 
After that,  STM 550 will take measurements  of  the ambient light  level using  its  solar cell 
every 5 seconds for a period of one minute and compute the average illumination based on 
those measurements. 
 
The  computed  average  illumination  is  then  available  in  the  NFC  register  ILLUMINA-
TION_TEST_RESULT as described in chapter 9.5.28. 
 
Illumination test mode can be selected using the MODE field of the FUNCTIONAL_MODE NFC 
register as described in chapter 9.5.11. 
 
2.2.6  Acceleration test mode 
 
During installation, STM 550 can visually indicate if detected acceleration exceeds the con-
figured threshold. This provides quick visual feedback about the correct installation as dis-
cussed in chapter 11.3. 
 
Upon activation of acceleration test mode, STM 550 will periodically (approximately every 3 
seconds) measure acceleration vector changes and blink the LED whenever this change ex-
ceeds the threshold configured using the ACCELERATION_THRESHOLD register as described 
in chapter 9.5.21. 
 
Acceleration test mode can be selected using the MODE field of the FUNCTIONAL_MODE NFC 
register as described in chapter 9.5.11 or using the LRN button as described in chapter 4.2. 
 
2.2.7  Factory reset mode 
 
STM 550 can be reset to its standard settings using factory reset mode. Upon entering this 
mode, STM 550 will reset all configuration registers to their default settings and then restart 
operation in standard operation mode. 
 
Factory reset mode can be selected using the LRN button as described in chapter 4.1 or using 
the MODE field of the FUNCTIONAL_MODE NFC register as described in chapter 9.5.11.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3 Reporting interval

STM 550 will transmit its status as data telegram at a regular interval, the so-called reporting

interval. By default, the reporting interval is 60 seconds, i.e. STM 550 will measure and report

its status approximately once per minute.

STM 550 is designed to apply fluctuations up to +-10% to any configured reporting interval

to increase transmission reliability and meet regulatory requirements.

If STM 550 is configured to report acceleration, then it will always report the initial accelera-

tion detection after a period without detected acceleration immediately. Likewise, if STM 550

is configured to report magnet contact status, then it will report any change in the status of

the magnet contact sensor (open -> closed or closed -> open) immediately.

2.3.1 Energy considerations

The default reporting interval of 60 seconds (one update per minute) is adjustable using the

NFC interface as discussed in the subsequent chapters. The minimum possible reporting in-

terval is 3 seconds and the maximum possible transmission interval is 65535 seconds.

Lowering the reporting interval of STM 550 will increase its power consumption since it will

measure and transmit more often. Likewise, increasing the reporting interval of STM 550 will

reduce its power consumption since it will measure and transmit less often.

To select the right reporting interval, it is essential to determine the amount of harvestable

energy. STM 550 harvests energy from the available ambient light; therefore, the available

energy is determined by intensity and availability (time) of available ambient light.

The ambient light intensity can be determined by executing an illumination test as described

in chapter 2.2.5. The ambient light availability period needs to be determined based on the

lighting scheme used for the environment where STM 550 is installed.

STM 550 is designed to provide to operate self-supplied in its default configuration (one

update every 60 seconds) based on 200 lux of ambient light available for 6 hours per day.

The minimum supported update interval for self-supplied operation based on other conditions

is summarized in Table 1 below. Sufficient margin should be added in case the light level

might change.

6 hrs / day

8 hrs / day

10 hrs / day

12 hrs / day

50 lux

Not supported

180 s

120 s

100 lux

120 s

90 s

60 s

150 lux

90 s

60 s

45 s

200 lux

60 s

45 s

30 s

300 lux

45 s

30 s

20 s

400 lux

30 s

25 s

15 s

500 lux

25 s

20 s

15 s

Table 1 – Minimum self-supplied reporting intervals

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3.2 Standard reporting interval

The standard reporting interval determines the default interval between two status updates

of STM 550.

The standard reporting interval can be adjusted using the STANDARD_TX_INTERVAL NFC

register as described in chapter 9.5.12. Consider the available energy before lowering the

reporting interval as discussed in chapter 2.3.1.

The default setting for the standard reporting interval is one status update once every 60

seconds (1 minute).

Figure 2 below illustrates the use of the standard reporting interval.

STANDARD_TX_INTERVAL STANDARD_TX_INTERVAL

Figure 2 – Standard reporting interval

STM 550 can be configured to use a lower reporting interval, i.e. provide updates more often,

based on certain conditions as described below.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3.3 Illumination-controlled reporting interval

If sufficient ambient light is available, then it might be desirable to receive status updates

more often. For this, there are typically two main use cases:

◼ Adjust the update rate based on the ambient light available for harvesting

◼ Report more often during daytime (or when an office is lit) and less often during

night-time (or when an office is dark) to adapt the reporting to the usage pattern

In both cases, the higher update rate would be used whenever the ambient light level is

above a certain threshold. Figure 3 below illustrated the use of the illumination-controlled

reporting interval.

STANDARD_TX_INTERVAL SOLAR_CELL_TX_INTERVAL STANDARD_TX_INTERVALSOLAR_CELL_TX_INTERVAL

LIGHT_SENSOR_TX_INTERVAL LIGHT_SENSOR_TX_INTERVAL

Figure 3 – Illumination-controlled reporting interval

STM 550 can use either the light level at the solar cell (harvested energy) or the light level

at the ambient light sensor to trigger a higher update rate. To enable this feature, use the

following steps:

1. Configure the desired light level threshold either for the solar cell or the ambient

light sensor using either the SOLAR_THRESHOLD or LIGHT_THRESHOLD registers

described in chapters 9.5.17 and 9.5.19 respectively

2. Configure the desired reporting interval using either the SOLAR_TX_INTERVAL or

the LIGHT_TX_INTERVAL registers described in chapters 9.5.18 and 9.5.20 respec-

tively

3. Enable the use of the defined parameters using the SOLAR CELL and LIGHT SENSOR

bit fields in the THRESHOLD_CFG1 register of the NFC interface as defined in chap-

ter 9.5.13.

Consider the available energy before lowering the reporting interval as discussed in chapter

2.3.1.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3.4 Temperature-controlled reporting interval

In HVAC (heating, ventilation, air conditioning) applications it might be desirable to receive

status updates more often if the measured temperature is significantly above or below the

target value.

Figure 4 below illustrates the use of the temperature-controlled reporting interval.

Figure 4 – Temperature-controlled reporting interval

STM 550 can use the temperature measured by the temperature and humidity sensor to

trigger a higher update rate. To enable this feature, use the following steps:

1. Make sure that the EEP selected using the EEP register as described in chapter 9.5.8

reports the measured temperature

2. Configure the desired temperature threshold using the TEMPERATURE_THRESHOLD

register described in chapter 9.5.23

3. Configure the desired reporting interval using the TEMPERATURE_TX_INTERVAL reg-

ister described in chapter 9.5.24

4. Enable the use of the defined parameters using the TEMP SENSOR bit field in the

THRESHOLD_CFG1 register of the NFC interface as defined in chapter 9.5.13.

Consider the available energy before lowering the reporting interval as discussed in chapter

2.3.1.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3.5 Humidity-controlled reporting interval

In HVAC (heating, ventilation, air conditioning) applications it might be desirable to receive

status updates more often if the measured humidity is significantly above or below the target

value.

Figure 5 below illustrates the use of the humidity-controlled reporting interval.

Figure 5 – Humidity-controlled reporting interval

STM 550 can use the humidity measured by the temperature and humidity sensor to trigger

a higher update rate. To enable this feature, use the following steps:

1. Make sure that the EEP selected using the EEP register as described in chapter 9.5.8

reports humidity

2. Configure the desired humidity threshold using the HUMIDITY_THRESHOLD register

described in chapter 9.5.25

3. Configure the desired reporting interval using the HUMIDITY_TX_INTERVAL register

described in chapter 9.5.26

4. Enable the use of the defined parameters using the HUMIDITY SENSOR bit field in

the THRESHOLD_CFG1 register of the NFC interface as defined in chapter 9.5.13.

Consider the available energy before lowering the reporting interval as discussed in chapter

2.3.1.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3.6 Acceleration-controlled reporting interval

If an asset is in operation or it is being moved, then it might be desirable to receive status

updates more often to determine its status or location.

Figure 6 below illustrates the use of the acceleration-controlled reporting interval.

STANDARD_TX_INTERVAL ACCELERATION_TX_INTERVAL

STANDARD_TX_INTERVAL

Immediately

ACCELERATION_TX_INTERVAL

Figure 6 – Acceleration-controlled reporting interval

STM 550 can use acceleration events detected by the acceleration sensor to trigger a higher

update rate. To enable this feature, use the following steps:

1. Make sure that the EEP selected using the EEP register as described in chapter 9.5.8

reports acceleration

2. Configure the acceleration sensor parameters (full scale value and sampling fre-

quency) and enable the wake-on-acceleration feature using the ACC_SENSOR_CFG

register described in chapter 9.5.16

3. Configure the desired acceleration threshold using the ACCELERATION_THRESHOLD

register described in chapter 9.5.21

4. Configure the desired reporting interval using the ACCELERATION_TX_INTERVAL

register described in chapter 9.5.22

5. Enable the use of the defined parameters using the ACCELERATION SENSOR bit field

in the THRESHOLD_CFG2 register of the NFC interface as defined in chapter 9.5.14.

Consider the available energy before lowering the reporting interval as discussed in chapter

2.3.1.

USER MANUAL

STM 550 / EMSI – ENOCEAN MULTISENSOR FOR IOT APPLICATIONS

2.3.7 Magnet contact sensor-controlled reporting interval

If a door or a window is opened when it normally should be closed (or vice versa), then it

might be desirable to receive status updates more often to monitor its status. STM 550 can

therefore be configured to use a lower reporting interval, i.e. a higher update rate, for one

of the two magnet contact sensor status options (open or closed).

Figure 7 below illustrates the use of the magnet contact sensor-controlled reporting interval.

Figure 7 – Magnet contact sensor-controlled reporting interval

STM 550 can use the status of the magnet contact to trigger a higher update rate. To enable

this feature, use the following steps:

1. Make sure that the EEP selected using the EEP register as described in chapter 9.5.8

reports the magnet contact status

2. Configure the desired reporting interval using the MAGNET_CONTACT_TX_INTERVAL

register described in chapter 9.5.22

3. Select the state of the magnet contact (open or closed) where the lower update in-

terval should be active using the MC SENSOR bit field in the THRESHOLD_CFG2 reg-

ister as defined in chapter 9.5.14.

Consider the available energy before lowering the reporting interval as discussed in chapter

2.3.1.

2.3.8 Arbitration between reporting intervals

If more than one condition for a lower reporting interval applies – e.g. both an acceleration

exceeding the acceleration threshold is detected and the room is brightly lit in excess of the

light level threshold – then the lowest of the corresponding reporting intervals will be se-

lected.

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